Axial piston machine



Sept 22, 1964 w. GREGOR AXIM. PIsToN MACHINE Filed April 17, 1960 Jnvenor: mii/n." 64560;?

United States Patent C) 3,149,577 AXIAL PISTN MACHINE Wilhelm Gregor, Hamburg-Hausbruch, Germany, as-

signor to Licentia Patent-verwaltungs-Gmbl., Frankfurt am Main, Germany Filed Aug. 17, 1960, Ser. No. 50,105 Claims priority, application Germany Aug. 24, 1959 Claims. (Cl. 1026-162) The present invention relates to an axial piston machine. More particularly, the invention relates to an axial piston machine adapted to be used for a variety of purposes, for

- example, as a hydraulic motor or pump.

Heretofore known machines of the above type comprise a cylinder block about whose longitudinal axis there are arranged a plurality of individual cylinders which eX- tend substantially parallel to and in radial symmetry with respect to the longitudinal axis of the cylinder block. The cylinders are pivotally connected to the cylinder block and a special drive coupling is required for connecting the cylinder block with a driving or swash plate. In general, this coupling has to be in the form of a double universal joint or linkage so that even when the cylinders are oblique with respect to the driving plate, they will still be driven at a uniform rotational speed.

Although such double joints or linkages are sometimes used in axial piston machines having a single cylinder drum instead of individual cylinders, it has been found simpler to provide other means for rotating the drum, such as by letting the connecting rods which are attached to the pistons drive the drum directly, these connecting rods being supported either on the pistons themselves or on correspondingly formed retaining cups of the ball joints built into the piston. However, this advantageous type of construction is not possible in axial piston machines having individual cylinders pivotably connected to the cylinder block, inasmuch as there are no connecting or piston rods.

It is, therefore, an object of the present invention to provide an axial piston machine which has individual cylinders but which does not require a double driving linkage.

It is another object of the present invention to provide an axial piston machine capable of being operated either as a pump or as a motor, which machine is of sturdy construction, which will operate silently, which will give long periods of trouble-free service and which can be built at low cost. v

With the above objects in view, the present invention resides mainly in an axial piston machine having a cylinder block and a plurality of individual cylinders arranged about the longitudinal axis of the cylinder block and parallel thereto, which machine incorporates coupling means for the cylinders, these coupling means being on the cylinder block and acting transversely to the axes of the cylinders.

Additional objects and advantages of the present invention will become apparent upon consideration of the following description -when taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a longitudinal view through an axial piston machine according to the present invention, the cylinder block being shown in its extreme swung-out position.

FIGURE 2 is a longitudinal sectional view of the machine illustrated in FIGURE l, the view being in a plane at right angles to that of FIGURE l and the cylinder block being depicted in its swung-in position. l

FIGURE 3 is a diagrammatic illustration of the coupling means incorporated in the machine shown in FIG- URES 1 and 2, as seen in the direction of the longitudinal axis ofthe cylinder block.

3,149,577 Patented Sept. 22 1964 ICC FIGURE 4 is a fragmentary View showing a modification of the coupling means.

Referring now to the drawings, there is shown a driving plate 1 supported in a stationary bearing block 2 for rotation about an axis a. When the machine is used as a pump, this driving plate 1 is driven by an appropriate source (not shown). A cup-shaped housing 3 is pivotally connected to the bearing block 2 by means of pivot bearings 11. A cylinder block 4 is arranged within the housing 3 and is rotatable about a longitudinal axis b, appropriate ball bearings 5 being interposed between the cylinder block 4 and the bottom of the cup-shaped housing 3. The axes a and b intersect each other and the angle they form with each other depends on the inclination of the housing 3 with respect to the bearing block 2.

The cylinder on center block 4 carries a plurality of individual cylindrical members 6, hereinafter referred to simply as cylinders, which are arranged substantially parallel to the longitudinal axis b and therefore to each other. The cylinders are arranged in radial symmetry with respect to the axis b and ball joints 7 are provided which pivotally connect each cylinder 6 at one of its ends to the cylinder block 4. Each cylinder 6 has a piston 8 slidably arranged therewithin, the lower ends of the pistons being pivotally connected to the driving plate 1 by means of ball joints 9.

The lower end face of the cylinder block 4 carries a iluted template 10 whose shape resembles that of a sprocket wheel. This template 10, which is also in radial symmetry with the axis b, serves as a coupling or abutment means Within whose concave portions the lower ends of the cylinders d are received. The interengagement between the template and the cylinders is beaded. In the embodiment of FIGURES l and 2 the lower ends of the cylinders 6 are beaded at those portions 12 thereof at which they engage the template 10, whereas in the embodiment of FIGURE 4 the template 11) attached to the cylinder block 11194 is beaded at those portions 112 at which it engages the cylinders 1%. In either event, the flanks of the teeth 13 presented by the template are so designed that, when the housing 3 is in its swung-in position shown in FIGURE 2, they fit against the cylinders with as little free play as possible. v

When the driving plate 1 is rotated, the pistons 8 which are mechanically connected to the plate 1, as well as the cylinders 6, will be carried along. As the cylinders 6 are connected at one end to the cylinder block 4 by means of the ball joints '7, they would, without the coupling or abutment means according to the present invention, assume an oblique position. This is undesirable in View of the hydraulic forces acting on the parts. However, thanks to the above described coupling means, which are adapted to engage each of the cylinders 6 at a point spaced froml In the extreme swung-out position, just one cylinder` and its piston will take over the motion transmission within a range of (360/z), where z is the number of cylin-l ders e. This particular cylinder-will then be received virtually without play in the corresponding concave portion of the template 10, while the other cylinders will be spaced a greater or lesser distance from the corresponding concave portions of the template.

The number of cylinders serving as motion transmitting elements increases as the angle between the axes a and b decreases. At the same time, there takes place an increasing if negligible angular displacement of the cylinder block 4 with respect to the driving plate l.. This angular displacement reaches its maximum when the axis b of the cylinder block 4 coincides with the axis a of the driving plate 1, whereupon all of the cylinders will simultaneously abut the template 10.

As stated above, either the cylinders or they coupling means are beaded. The reason for this is to prevent end pressures resulting from the small pendular movements, ile., hunting due to kinematic conditions, of the pivotally mounted cylinders 6 relative to the axis b during rotation of the driving plate 1.

Heretofore, the linkages in axial piston machines had to be made of metal in order to enable the parts to withstand the hydraulic requirements. This, however, does not apply to a machine according to the present invention wherein the template 10 is not subjected to any hydraulic pressure. Therefore, the template can be made of a material whose selection is dictated by other considerations. For example, the template can be made of vibratien damping or shock absorbing non-metallic material as, for example, a plastic. Consequently, the machine will operate more quietly than a machine incorporating metallic parts only.

The present invention is not limited to an arrangement wherein the coupling means are constituted by a separate template of the type described above. instead, the coupling means can be integral with the cylinder block d, in which case the coupling means can be either ring shaped or comprise annular segments.

lt will be understood that the above description of the present invention is susceptible to various modilications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

I claim:

1. ln an axial piston machine, the combination which comprises: a center block having a longitudinal axis; a plurality of individual cylindrical members arranged about said axis, the axes of said cylindrical members being substantially parallel to said longitudinal axis of said center block, each of said cylindrical members being pivotally connected at one end thereof to said Vcenter block; and coupling means connected to said center block, projecting in between and engaging said cylindrical members, and acting transversely to said axes of said cylindrical members for preventing said cylindrical members from assuming an oblique position relative to said center block.

2. Inan axial piston machine, the combination which comprises: a center block having a longitudinal axis; a plurality of individual cylindrical members arranged about said axis, the axes of said cylindrical members being substantially parallel to said longitudinal axis of said center block; means pivotally connecting each cylindrical member at one end thereof to said center block; and coupling means connected to said center block, acting transversely to said axes of said cylindrical members and projecting in between said cylindrical members to engage each of the latter at a point thereof spaced from said one end thereof for preventing said cylindrical members from assuming an oblique position relative to said center block.

3. In an axial piston machine having a center block and a plurality of individual cylindrical members arranged about the longitudinal axis of said center block and parallel thereto, each of said cylindrical members being pivotally connected at one end thereof to said center block, the improvement comprising coupling means for said cylindrical members, said coupling means being connected to said center block, projecting in between and engaging said cylindrical members, and acting transversely to the axes of said cylindrical members for preventing said cylindrical members from assuming an oblique position relative to said center block.

4. The improvement dened in claim 3 wherein said coupling means are ring shaped.

5. The improvement deiined in claim 3 wherein said coupling means comprise annular segments.

6. The improvement deined in claim 3 wherein said coupling means comprise a template attached to said center block and being in radial symmetry with said longitudinal axis thereof.

7. The improvement defined in claim 3 wherein the interengagement between said coupling means and cylin`J drical members is beaded.

8. The improvement deined in claim 3 wherein said coupling means are beaded at those portions thereof at which they engage said cylindrical members.

9. The improvement defined in claim 3 wherein said cylindrical members are beaded at those portions thereof at which they engage said coupling means.

10. The improvement defined in claim 3 wherein said coupling means are lluted and within whose concave portions said cylindrical members are received.

11. The improvement deiined in claim 10 wherein said coupling means have the shape of a sprocket wheel.

12. The improvement deiined in claim 3 wherein said coupling means comprise a fluted template attached to said center block and being in radial symmetry with the longitudinal axis thereof, said cylindrical members being received within the concave portions of said template.

13. The improvement deiined in claim 3 wherein said coupling means are made of vibration damping material.

14. The improvement defined in claim 13 wherein said coupling means are made of non-metallic material.

15. In an axial piston machinethe combination which comprises: a Center block having a longitudinal axis; a plurality of individual cylinder members arranged about said axis, the axes of said cylinder members being substantially parallel to said longitudinal axisV of said center block; means pivotally connectingreach cylin er member at one end thereof to said center block; coupling means connected to said center block, acting transversely to said axes of said cylinder members and projecting in between said cylinder members to engage eachrof the latter at a point thereof spaced from said one end thereof for preventing said cylinder members from assuming an oblique position relative to said center block; a plurality of piston members slidably arranged in said cylinder members, respectively; anddriving means for moving said cylinder and piston members relative to each other to produce a pumping action.

References Cited in the ille ofrthis patent UNITED STATES PATENTS Y Great Britain Feb. 25, 

1. IN AN AXIAL PISTON MACHINE, THE COMBINATION WHICH COMPRISES: A CENTER BLOCK HAVING A LONGITUDINAL AXIS; A PLURALITY OF INDIVIDUAL CYLINDRICAL MEMBERS ARRANGED ABOUT SAID AXIS, THE AXES OF SAID CYLINDRICAL MEMBERS BEING SUBSTANTIALLY PARALLEL TO SAID LONGITUDINAL AXIS OF SAID CENTER BLOCK, EACH OF SAID CYLINDRICAL MEMBERS BEING PIVOTALLY CONNECTED AT ONE END THEREOF TO SAID CENTER BLOCK; AND COUPLING MEANS CONNECTED TO SAID CENTER BLOCK, PROJECTING IN BETWEEN AND ENGAGING SAID CYLINDRICAL MEMBERS, AND ACTING TRANSVERSELY TO SAID AXES OF SAID CYLINDRICAL MEMBERS FOR PREVENTING SAID CYLINDRICAL MEMBERS 